测厚电离室的研制

本文介绍了测量金属及非金属材料厚度的测厚电离室系列的原理、结构及各种性能。它们可以用来测量10-6000g/m~2的各种薄材料厚度以及复合材料表面层的厚度,也可以测量不大于32kg/m~2钢板的厚度。     

平面结终端场位分析的数值方法综述

本文对高压平面结终端结构优化设计中采用的各种数值方法开展了分析和比较，总结了 其中的一般性规律，对终端结构优化设计的发展提出了自己的看法。     

Mechanisms of detection and imaging in the ESEM

For proper understanding of image formation using charge carriers, it is shown that signal detection by means of induction must be considered. This explains the possibility of imaging insulators as well as other phenomena especially in the conditions of the environmental scanning electron microscope. In addition, a basic principle and method to separate the secondary and backscattered electrons is demonstrated.     

Residual donors and acceptors in high-purity GaAs and InP grown by hydride VPE

Residual donors and acceptors in epitaxial films of GaAs and InP grown by the hydride vapor phase epitaxy technique were investigated using the complementary techniques of photothermal ionization spectroscopy and variabletemperature photoluminescence. High-purity samples of GaAs grown in three different laboratories were compared and high-purity InP samples were also measured. The dominant shallow acceptors in the GaAs samples were found to be C and Zn, and deep Cu and Mn acceptors were also observed. The donors Si, S, and Ge were observed in the GaAs with S being dominant. A clear correlation was observed between the gas phase stoichiometry during growth and the relative incorporation of column IV donors (Si and Ge) and column VI donors (S) in GaAs. Substrate quality, source purity, and atmospheric contamination of the growth system were found to influence the photoluminescence spectra of the GaAs samples. In the InP samples three shallow acceptors were observed including Zn, an unknown shallow acceptor level with E_A ≃ 21 meV, and an acceptor which may be either C or Mg. An unusual deep, structured emission band was also seen. The donors in the hydride InP were also found to be present in LPE InP and are believed to be Si and S.     

The determination of impact ionization coefficients in ln0.2Ga0.8As/GaAs strained-layer superlattice mesa photodiodes

Sandia National Laboratories, Albuquerque, NM 87185 Photocurrent multiplication measurements have been performed on two different In_0.2Gao_0.8As/GaAs strained-layer superlattice (SLS)p ⁺n photodiode structures which are designed to permit simultaneous injection of electrons and holes. Initial devices were found to suffer from low quantum efficiencies produced by small electron diffusion lengths as well as mixed injection caused by lower than expected optical absorption coefficients in the SLSn ⁺ contact layers for hole injection conditions. Using a second device structure having a thicker n⁺ contact region, the electron multiplication factors are found to be larger than that of holes with a ratio of the electron to hole ionization coefficient of 1.4 for fields between 2.9 and 3.4 x 10⁵V/cm.     

氧离子与氖原子碰撞转移电离过程研究

采用位置灵敏探测和散射离子-反冲离子飞行时间测量技术，测量了氧离子与氖原子碰撞过程中转移电离截面与单电子俘获截面之比。通过比较，发现测量结果与文献结果的趋势一致，并对测量结果进行了解释。     

苯乙基丙二酸的合成及其电离常数研究

合成了苯乙基丙二酸，经红外光谱、元素色谱、熔点测定等分析手段对合成产物进行了表征，用ＰＨ－电位滴定法测定了该配体在二恶烷／水混合介质中（Ｖ／Ｖ％）以ＫＮＯ３为支持电解质及离子强度Ｉ＝０．１０ｍｏｌ．ｄｍ＾－３条件下的一、二级电离常数，并与相似的丙二酸电离常数进行了比较。结果表明：随着溶剂中二恶烷比例的增大，苯乙基丙二烷和丙二酸的各极电离常数ＰＫ值亦成比例增大，符合线性变化规律。     

激光光解NO2产物的NO分子之离子谱研究

利用Nd：YAG激光器三倍频，输出波长为λ=355nm的激光光解NO2分子所产生的NO分子，通过共振增强多光子电离及飞行时间质谱技术，获得了振转态分辨的NO(X^2Ⅱ，v“,J“)离子谱NOγ(0，0)，γ(1，0)，γ(1，1)。NO分子的离子信号强度与UV电离激光能量(λ≈226nm)之间的关系能用二次方曲线很好拟合，它表明光解产物NO分子是通过(1 1)多光子吸收过程而被电离的。上述结果对NO2分子光解动力学及其产物NO的电离动力学提供了十分有益的信息。     

支持气体对弧放电离子源的有益作用

在弧放电等离子体离子源中,用支持气体改善离子源的工作已有三十年的历史。美国ORNL在Calutron源中引进N_2或惰性气体。1973年Freeman提出,蒸汽未放电时,先用惰性气体帮助放电,直到蒸汽能建立放电时就停止供气。1977年Hudson等报道了用支持气体提高Ne~(6 )流强。但是,支持气体在弧放电离子源中的作用,至今尚未深入研究,